The SP2's high sensitivity, fast response, and specificity to elemental carbon make it the premier instrument for characterizing air pollution sources and documenting thin atmospheric layers of contamination. It is also ideal for measuring soot in snow, ice or water and for calibrating other black carbon-measuring instruments like the Aethalometer.

New Features

DMT recently released version D of the SP2. The instrument now features an i7 processor with 8GB RAM. This more powerful computer allows the SP2 to measure much higher particle concentrations. It will not lose particles until particles become coincident. Other new features are listed below.

Larger 750 GB hard drive

Universal power supply for easier international campaigns

Integrated laser and temperature control for greater reliability

Software control of the sample pump

Additional housekeeping channels

Additional USB ports (six instead of two)

Additional RS-232 port (two instead of one)

Additional Ethernet port (two instead of one)

HDMI monitor port in addition to VGA port

Software

Standard SP2 Software

The SP2 comes with a software program that provides a user-friendly virtual instrument panel for the control, data display, and data logging of the SP2 instrument. For instance, the program enables the user to do the following tasks:

View graphs of incandescence and scattering signals from individual particles

View the incandescent particle concentration over the last 30 minutes

Monitor parameters like YAG laser power and flow measurements

Change the charts and data channels displayed in the software

Filter data that is saved to the output file so it includes only specific types of particle events

Probe Analysis Package for Igor (PAPI)

The SP2 also comes with a free copy of the Probe Analysis Package for Igor (PAPI). This program facilitates SP2 data analysis in several ways:

Processing SP2 binary files and collecting particle-peak statistics

Automating much of the SP2 calibration process

Calculating common statistics such as black carbon mass and number concentrations, black carbon number fraction, and ensemble measurements

Allowing user to select size bins with resolutions as fine as 5 nm (for both incandescent and scattering measurements)

How it Works

The SP2 uses the high optical power available intra-cavity from an Nd:YAG laser. Light-absorbing particles containing mainly black or elemental carbon absorb energy and are heated to the point of incandescence. The incandescent emission is measured and correlated to the particle’s black carbon mass with the help of black carbon proxies like Aquadag or fullerene soot.

The SP2 also includes a scattering detector, which detects single-particle light-scattering at 1064 nm. The scattering signal can be used to indicate particle size and the black carbon mixing state at the single-particle level. The scattering detector can also be used to detect non-BC-containing aerosol number and mass concentrations.

The full scattering and/or incandescence response of each particle is completely digitized for detailed analysis.

Specifications

Parameter

Specification

Measured Parameters

Single-particle laser incandescence
Single-particle light scattering

Auxiliary Parameters

Temperature
Pressure

Derived Parameters

BC mass distribution as function of particle diameter
Particle number distribution as a function of particle size

Nd:YAG Laser: 1064 nm, 3 MW/cm2 intracavity circulating powerPump Laser: 808 nm, 4 W
The pump laser can be controlled either through the SP2 software or through the touch-screen on the SP2 front panel.)

Sample Flow

30 – 180 volumetric cm3/minute (typically 120)

Flow Control

Electronic flow control with a laminar flow element (LFE) and a solenoid valve

Pump

Two single-head diaphragm pumps encased in a box

Minimum Black Carbon Detection Limit

10 ng/m3

0.3 fg/particle

Calibration

DMT recommends calibrating the SP2 every six months and/or before and after every field campaign.

The incandescence measurement is calibrated to black carbon mass using DMA-sized Aquadag, fullerene soot or glassy carbon. (DMA refers to differential mobility analyzer, used to extract particles of a single electrical mobility size from a polydisperse aerosol.)